This Specialized Resource will provide chemical expertise and produce imaging agents that are not commercially available. These agents will be a) rigorously tested so as to conform to strict standards (by being synthesized under standardized conditions in technically adequate ways); b) analyzed according to a standard protocol prior to use; and c) synthesized in sufficient amounts for in vivo use. They will be available to all Project researchers. As it has in the past, this Resource will also conduct its own research in order to further improve synthetic conditions, and to design fluorochromes, sensors, tags, linkers and nanoparticulate carriers. The specific aims of this Specialized Resource are to synthesize and provide: 1) an array of new fluorochromes, fluorescently labeled reagents, sensors, and coupling reagents; 2) nanomaterial based imaging agents; and 3) radiochemistry expertise and novel ''^F-imaging agents. The existence of this Specialized Resource has a number of benefits to the overall Program, these include: a) access to cutting edge synthetic, bioconjugate and analytical chemistry; b) access to radiochemistry; c) access to well validated imaging compounds that are not commercially available; d) capabilities for scaling up the synthesis of novel compounds; and e) access to specific training. By centralizing personnel, resources and supplies, the Chemistry Resource is able to provide these functions extremely efficiently and at a reduced overall cost.